[Wien] specific heat factor

[Ruben Weht]

Dear Peter,

I think Jan is right and there is an error in the gamma formula.

I think Gamma is  (1/3).pi^2.kb^2.Na

where kb is the Bolztmann constant and Na Avogadro's number.

As Gamma is in general in units of  mJ/k^2.mol
and density of states in   states/Ry
you can take one kb in each energy unit.

In this way   kb = 1.3806503.10^-20  mJ/K 
and           kb = 6.3336303.10^-6   Ry/K
              Na = 6.0221.10^23      1/mol

So   Gamma = 0.17324706  mJ.Ry/K^2/mol

I hope it helps,
Best,

   Ruben

>> There is the electronic specific heat C_v/T, which is for
>> non-interacting electrons propotional to the density of states
>> at Fermi level, printed out in the output of tetra. I find the
>> convesion factor from N(E_F) in 1/Ry to gamma in mJ/(K^2 mol)
>> strange:
>>
>> gamma=N(E_F)/2.d0*(8.617D-5)
**2*pi**2)/3.d0*2.6255D6/27.212d0*1000.d0
>>
>> does anybody know where the 2.6255D6 comes from? By the way
>> conversion factor I normally use is
>> gamma[mJ/K^2/mol]=0.173*N(E_F)[1/Ry] (quite different from wien
>> value).
> 
> Well, Georg seems to have programmed a "secret" here.
> 
> To my understanding the conversions require k_B, Avogadros number
> and E-conversions into J
> 
> 2.6255D6:  This factor arises from two (or actually 3) numbers:
> Avogadros number (6.022 10^23 /mol)
> the energy conversion from "atomic units" to Joule, which is
> 
> 27.212 * 1.60219 10^-19    (first converts hartree into eV, than
> eV into J)
> 
> PS: The (8.617D-5)**2 is k_B in (eV/K)^2   and this leads to this
> additionl factor of 1/27.212 ....
> 
> And somewhere are hidden the factors of 2 from Ry to hartree....
> 
> Hope it fits like this. Just check it on a simple case (Cu or
> so), where the gamma0 is well known.
> 
>                                       P.Blaha
> -------------------------------------------------------------------
-------
> Peter BLAHA, Inst.f. Materials Chemistry, TU Vienna, A-1060
> Vienna Phone: +43-1-58801-15671             FAX:
> +43-1-58801-15698
> Email: blaha at theochem.tuwien.ac.at    WWW:
> http://info.tuwien.ac.at/theochem/
> -------------------------------------------------------------------
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|  Ruben Weht                                   |
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